Batching with feedback correction

ABSTRACT

A method and apparatus are disclosed for automatically batching objects into portions, comprising conveying and weighing objects. An appropriate bin for each of the weighed objects is selected, wherein each bin is provided with a weighing means. Accordingly, the total portion weight is periodically registered. By means of comparing the potion weight with the summed object weight in that portions, an appropriate bin can be selected for forthcoming objects.

This application is the U.S. national phase of international applicationPCT/IS03/00008 filed on 13 Feb. 2003, which designated the U.S. andclaims priority to IS Application No. 6268 filed 13 Feb. 2002. Theentire contents of these applications are incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates to a method and an apparatus forautomatically batching objects into portions with a feedback correction.

BACKGROUND

In various industries, basic objects are sold in batches satisfyingvarious constraints. For example, many food objects, such as fresh orfrozen fish portions, chicken portions or meat portions, are sold inprepackaged batches having a predetermined weight and/or number ofpieces, within given tolerance. The tolerances may be quite strict insome industries.

In the contracts between sellers and purchasers for delivery of productsmust satisfy minimum weight or other requirements. It is important thatnone of the collections is below minimum weight, but exceeding theweight results in an economical loss for the manufacturer.

The typical way to build up portions of objects is to weight each objectprior to selecting the appropriate portion that is building up thisparticular object, where the weight of each portion is simply the sum ofeach individual object In that portion. If all the portions are far fromthe final weight limit, it is not essential which of these portions willbe chosen for this object. If however the weight of one or more portionsis closed to the final weight limit, it is essential which portion, forthis particular object, will be chosen.

GB A 2.115.630 describes system for portion weighing of material whereinan automatic feedback correction is Introduced to correct the weighingdifference between continues weighing and stationary weighing. U.S. A3,945,448 describe similar system. As discussed hereinafter there is thefundamental difference between those prior systems, which do not allowselection of objects to be directed into preferred bin according to itsfirst weight as well as corrected weighing for prior items alreadydirected to a plurality of bins.

The problem with prior art methods is the inaccuracy in the weight ofeach portion that is building up, which can change the precondition whenselecting an appropriate objects into a portion, so that the overweightof that portion is minimized. Where the weight of one portion is basedon the sum of each object in the portion, the error in the weight of thetotal portion is the sum of errors in of each individual object. Thiscan be related to the resolution in the weighing means that are beingused. As an example the resolution in a weighing means is 1 g. Thismeans that the error in weighing a single object is up to 1 g. If thenumber of objects in one portion is 20, the maximum error is number ofobjects multiplied with the resolution (error) for one single object, or20*2 g=40 g. However, by registering the weight of the total portion bya single weighing procedure this error is dramatically reduced, andwould in this particular example be 1 *1 g=1 g.

DESCRIPTION OF THE INVENTION

It is an object of the present invention to provide an apparatus and amethod for reducing this error by registering the weight the totalportion that is building up, instead of relying on the sum of weights ofeach individual object. The portion weight can therefore be used forre-estimating physical characteristic for use with future weighing data.Thereby the error is reduced dramatically in the weighing procedure.

According to the first aspect, the present invention relates to a methodfor automatically batching objects into portions, comprising:

-   -   conveying a present object to be weighed,    -   weighing said present object to be graded and sending output        signals representative of the weighing data,    -   selecting an appropriate bin for said weighed object where a        portion of at least one object is formed,    -   directing said object to said bin,    -   weighing said portion periodically and sending output signals        representative of the weighing data,    -   comparing said portion weight periodically with the summed        object weight in said bin, and    -   utilizing a plurality of such comparisons for selecting an        appropriate bin for forthcoming objects and thereby increasing        weighing accuracy in the bin.

Preferably comparing the portion weight with the summed object weightcomprises determining the difference there between. If the differenceexceeds a predetermined limit the weighing of objects may be corrected,with the aim of minimizing the later determined differences between theportion weight and the summed object weight. A difference there betweencan also Indicate a whether a particular items has been replaces in notselected bin for that particular item. Selecting an appropriate bin forsaid weighed object is base on statistical method, but is not essentialhere. Selecting an appropriate bin for said weighed object may alsocomprise generating at least one portion until an upper weight limitbelow a target weight limit is reached and subsequently selecting anappropriate object with the aim of minimizing the overweight.

In another aspect, the present invention relates to an apparatus forautomatic grading of objects into portions, comprising:

a conveyor for conveying the objects;

a first weighing equipment for weighing the object to be graded as theobject is conveyed on said conveyor, said weighing equipment sendingoutput signals representative of the weighing data;

means for determining an appropriate bin for said weighed object where aportion of at least one object is formed,

a second weighing equipment for weighing a portion weight of saidobjects in at least one bin, said weighing equipment sending outputsignals representative of the weighing data;

a computer system utilizing said output signals representative of saidweight data for comparing said portion weight periodically with thesummed object weight in said bin, and

said computer system utilizing a plurality of such comparisons forselecting an appropriate bin for forthcoming objects.

Preferably the first weighing equipment is a dynamic scale and thesecond weighting equipment is a static scale. The present invention alsoprovides a method in claims 1-6.

DETAILED DESCRIPTION

The above and other objects and advantages of the invention will beapparent upon consideration of the following detailed description, takenin conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 shows one embodiment of an apparatus for batching objects usingportion weight to correct the actual object weight. In this embodimentthe objects 9 are weighed on a weighing means 10, such as a dynamicscale. A weighing signal is directed to the computer system 6. Basedupon the weighing of the particular object, previously weighed objectsas well as information obtained about the accumulated weighing 12 in thebin and weighing criteria such as maximum overweight, the objects areaccordingly directed them into a bin. The conveyor 1 with arm devices 3is associated to appropriate bins 4. The decision of selecting theappropriate bin may 4 be based on any known methods for example such asstatistical methods. This is however not the essential part of thepresent invention. The essential feature here is the weighing means thatis provided for weighing the portion in each of the bins 4. This reducesthe error dramatically wherein the resolution in the weighing means isusually based on resolution error. This may be explained further in thefollowing example: The weigh of one object is (22 ±1) g, wherein due tothe resolution In the weighing means the error is 1 g. If the portionweight consists of 5 pieces, 22 g, 23 g, 19 g, 20 g and 25 g, the totalweight is (109 ±5) g, wherein 5 g is the total error. Accordingly, thetotal error in the weight measurement is the sum of the error for eachindividual object. If on the other hand the whole portion as such isweighed such multiple error in the weight measurement does not occur,and the error is only be 1 g. Also, such weighing means for each bin maybe a static scale, which are usually more accurate than dynamic scales.

In the embodiment in FIG. 1, a plurality of objects 9, 11 are conveyedwith a conveyor belt 1 in a direction indicated by the arrow 2. Eachobject is weighed and the information are stored in a computer system 6.This computer system 6 receives also information regarding the portionweight 5 periodically, so at any instant of time the actual portionweight is known, and compares this portion weight with the total weightthat would be obtained by summing the weight of each individual objectin this particular portion 4. From the portion weights 5 and the objectweight 7 the computer system transfers the object with a directing arms3 into the appropriate bin. However, a difference between the portionweight 5 and the summed target weight between may be due to the largererror occurring in summing up the individual object. This error may alsobe due to failures in directing the objects into the right bin. If suchfailure would occur, it would be registered Instantly and appropriatearrangement could be made. If the difference is small, which could bedue to errors in the dynamic scale 10 a correction procedure in thescale could be done, until the difference between the portion weight 5the summed weight of each individual objects is minimized.

Assuming that no failures occur, and assuming that all the bins areempty, then the correction could be done in the following way:

An object nr.1 is weighed on the dynamic scale and has the value w1 andis put into bin 4, where the static scale weighs said object. Thisweight of the bin (with only one object) is compared to the weight fromthe dynamic scale. If the difference is very small, no correction In thestatic scale is necessary. An object nr. 5 is at some later time weighedwith the dynamic scale and has the value w5 is put into the same bin 4.The computer system compared now compare the portion valueportion=(w1+w2) with the summed value sum=w1+w2. If again the differenceportion—sum is within some predetermined limit, no correction in thedynamic scale is made. If on the other hand this difference exceeds saidpredetermined limit, the dynamic scale is corrected. Again thisprocedure is repeated and again the correction if necessary.

In another preferred embodiment, the batching may be based on fillingportions 4 up to a predetermined limit, which Is under a target weightlimit. Again the computer systems registers frequently the portionweight 5 and signals when the portion weight it is close to the targetweight limit. Thereafter, an appropriate object that has been weighed onthe dynamic scale is chosen for that particular bin so that theoverweight (the weight exceeding the target weight) is minimized.

1. A method for automatically batching objects into portions,comprising: conveying a present object to be weighed, weighing saidpresent object to be graded and sending output signals representative ofweighing data for the present object, selecting an appropriate bin forsaid weighed object where a portion of at least one object is formed,directing said object to said bin, weighing said portion periodicallyand sending output signals representative of weighing data for theportion, comparing said portion's weight periodically with a summedobject weight in said bin, and utilizing a plurality of such comparisonsfor selecting an appropriate bin for forthcoming objects and therebyincreasing weighing accuracy in the bin.
 2. The method according toclaim 1, wherein comparing the portion weight with the summed objectweight comprises determining the difference there between.
 3. The methodaccording to claim 2, wherein if the difference exceeds a predeterminedlimit the weighing of objects is corrected with the aim of minimizingthe later determined differences between the portion weight and thesummed object weight.
 4. The method according to claim 1, wherein thedifference between the portion weight and the summed object weight isused for determining if a particular item has been replaced in anon-selected bin for that particular item.
 5. The method according toclaim 1, wherein selecting an appropriate bin for said weighed object isbased on statistical methods.
 6. The method according to claim 1,wherein selecting an appropriate bin for said weighed object comprisesgenerating at least one portion until an upper weight limit below atarget weight limit is reached and subsequently selecting an appropriateobject with the aim of minimizing the amount of weight over the weightlimit.
 7. An apparatus for automatic grading of objects into portions,comprising: a conveyor for conveying the objects, a first weighingequipment for weighing the object to be graded as the object is conveyedon said conveyor, said weighing equipment sending output signalsrepresentative of weighing data for the object to be graded, means fordetermining an appropriate bin for said weighed object where a portionof at least one object is formed, a second weighing equipment forweighing a portion weight of said objects in at least one bin, saidweighing equipment sending output signals representative of weighingdata for said portion weight, a computer system utilizing said outputsignals representative of said weight data for comparing said portionweight periodically with a summed object weight in said bin, and saidcomputer system utilizing a plurality of such comparisons for selectingan appropriate bin for forthcoming objects and thereby increasingweighing accuracy in the bin.
 8. The apparatus according to claim 7,wherein the first weighing equipment is a dynamic scale.
 9. Theapparatus according to claim 7, wherein the second weighing equipment isa static scale.
 10. The apparatus according to claim 7, for performingthe method in claim 1.